A study of the reaction π−p → π−π+n at 16 GeV/c (original) (raw)

Coupled-channels study of the π-p→ηn process

Physical Review C, 2008

The reaction π − p → ηn is investigated within a dynamical coupled-channels model of meson production reactions in the nucleon resonance region. The meson baryon channels included are πN , ηN , π∆, σN , and ρN . The non-resonant meson-baryon interactions of the model are derived from a set of Lagrangians by using a unitary transformation method. One or two excited nucleon states in each of S, P , D, and F partial waves are included to generate the resonant amplitudes.

The reactions π±p→pπ±π+π− at 18.5 GeV/c

Nuclear Physics B, 1974

Studies have been made of the reactions n+p-+ pn+n+rr-and *r p-+ prr+rr rr , both at an incident pion momentum of 18.5 GeV/c. The two-body (primarily a++ and po) and three-body (low-mass A enhancement, A3, N* (1400), and N* (1700)) subsystems are discussed. Cross sections for all significant channels of the reactions are given.

Coupled-channels study of the pi- p ---> eta n process

Physical Review C, 2008

The reaction pi−ptoetan\pi^{-}p \to \eta npi−ptoetan is investigated within a dynamical coupled-channels model of meson production reactions in the nucleon resonance region. The meson baryon channels included are piN\pi NpiN, etaN\eta NetaN, piDelta\pi \DeltapiDelta, sigmaN\sigma NsigmaN, and rhoN\rho NrhoN. The non-resonant meson-baryon interactions of the model are derived from a set of Lagrangians by using a unitary transformation method. One or two excited nucleon states in each of SSS, PPP, DDD, and FFF partial waves are included to generate the resonant amplitudes. Data of pi−ptoetan\pi^{-}p \to \eta npi−ptoetan reaction from threshold up to a total center-of-mass energy of about 2 GeV are satisfactorily reproduced and the roles played by the following nine nucleon resonances are investigated: S11(1535)S_{11}(1535)S11(1535), S11(1650)S_{11}(1650)S11(1650), P11(1440)P_{11}(1440)P11(1440), P11(1710)P_{11}(1710)P11(1710), P13(1720)P_{13}(1720)P13(1720), D13(1520)D_{13}(1520)D13(1520), D13(1700)D_{13}(1700)D13(1700), D15(1675)D_{15}(1675)D15(1675), and F15(1680)F_{15}(1680)F15(1680). The reaction mechanism as well as the predicted etaN\eta NetaN scattering length are discussed.

The reaction π− p → π+ Δ− at CMS energies 1640–1760 MeV

Physics Letters B, 1971

A partial wave analysis of the quasi-two body reaction ~'-p-* A-~ "+ has led to two solutions. In both solutions, A and B, the total yTrN decay of the N*(D15) is accounted for by the AT channel whereas only , in solution B does the Air channel correspond to the total ~'~'N decay of the N (F15). The relative sign of the couplings of the resonances to A?r is also different between solutions, being negative in solution A and positive in solution B. The results are used to predict the decay rates of other members of the octets. An energy dependent partial wave analysis of the quasi-two body reaction

Highlights of the reaction π^{-} p→ π^{-} π^{+} n at 100 and 175 GeV/c

1984

We define the p by the same m m-mass cut, 0. 7~ m~ 0. 85 GeV, used in Ref. 8, and in Fig. 2 we compare the differential cross section for (2) at 17. 2, 100, and 175 GeV. We find asimilar shape at all energies and the cross section roughly scalesin the p~, b'fashion expect-ed from one-n exchange. We can use the measured density-matrix elements of the p to breakup the cross section into the contributions of different exchanges and find the (effective) Regge trajectories as a function of t for each component. There are three contributions C;.

A proposal to study resonance production in pi- p --> x -p at 40 to 80 GeV/c

We propose a study of do/dt vs. sand t for various known resonances in order to elucidate exchange mechanisms and the validity of strong interaction theories. We plan to study resonances with masses less than 2 GeV/c 2 having +-decay modes into 7T 7T 7T , 7T 7T o and 7T n° over the range 0.04 < It] < 0.55, for incident pion momenta from 40 to 80 GeV/c. This counter/wire-spark chamber experiment utilizes the excellent mass resolution at modest apparatus cost obtained by measuring the direction and energy of the recoil proton, and the directions of the fast secondary particles. The estimated resolution, between ±10 and ±50 MeV/c 2 , depends upon the precision with which y-conversion vertices can be determined. Moderate accuracy momentum measurements are included for the fast secondaries in order to add constraints. The experiment has two phases: I} a study of 7T+7T-7T-decays, using conventional wire plane tech .. , niques, and 2} a study of the modes involving y's, requiring a large y detection and localizing array.

Partial-wave analysis of the reaction πN→ππN in the c.m energy range 1300-2000 MeV

Physical Review D, 1975

A partial-wave analysis of the reaction~N-~N has been carried out in the energy region 1300-2000 MeV. Two continuous solutions have been found; they are very similar in regions where data exist, but differ in the continuation of amplitudes through a gap between our lowand high-energy data. The second solution ("B")gives a much better fit to the data. These new partial-wave amplitudes provide important information on the inelastic couplings of the nucleon resonances to the N p, ¹, and Dx channels. A new resonance, a&3(1700), long predicted by the quark model, has been observed coupling to two inelastic channels~N and 47(, and the existence of a P&3(1700) state is corroborated. Our preferred solution indicates a second new resonance, P33(1700), coupled strongly to the 4~channel.

Experimental study of theP11(1440)andD13(1520)resonances from the CLAS data onep→e′π+π−p′

Physical Review C, 2012

The transition helicity amplitudes from the proton ground state to the P11(1440) and D13(1520) excited states (γvpN * electrocouplings) were determined from the analysis of nine independent onefold differential π + π − p electroproduction cross sections off a proton target, taken with CLAS at photon virtualities 0.25 GeV 2 < Q 2 < 0.60 GeV 2. The phenomenological reaction model was employed for separation of the resonant and non-resonant contributions to the final state. The P11(1440) and D13(1520) electrocouplings were obtained from the resonant amplitudes parametrized within the framework of a unitarized Breit-Wigner ansatz. They are consistent with results obtained in the previous CLAS analyses of the π + n and π 0 p channels. The successful description of a large body of data in dominant meson-electroproduction channels off protons with the same γvpN * electrocouplings offers clear evidence for the reliable extraction of these fundamental quantities from meson-electroproduction data. This analysis also led to the determination of the long-awaited hadronic branching ratios for the D13(1520) decay into ∆π (24%-32%) and N ρ (8%-17%).